Cosmetic and/or pharmaceutical formulations with an improved feeling on the skin based on mixed guerbet alcohols

ABSTRACT

A cosmetic or pharmaceutical composition having an improved feel on the skin containing Guerbet alcohols based on fatty alcohol mixtures containing 6 to 12 carbon atoms or esters thereof with fatty acids containing 6 to 22 carbon atoms as oil components, wherein the spreading value of the oil components as determined by the Zeidler method is from about 300 to about 1,000 mm 2  /10 minutes.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to new cosmetic and/or pharmaceuticalformulations which contain as oils Guerbet alcohols based on short-chainfatty alcohol mixtures or esters thereof with selected fatty acids.

2. Discussion of Related Art

The production of cosmetic or pharmaceutical formulations, for examplecreams, lotions or emollients, involves the use of oil-soluble bases ofwhich the function is to transport polar ingredients, for example activesubstances or moisture, through the lipid barriers of the skin. Variousnatural and synthetic oils, for example almond oil or avocado oil orester oils based on short-chain triglycerides, are suitable for thispurpose. The oil components in the formulations in question also performa skin-care function which is directly related to oiling of the skin.There is a demand among consumers for products which impart a non-tacky,almost instantaneous and relatively long-lasting feeling of smoothnessand suppleness to the skin.

The subjective feeling on the skin can be correlated and objectifiedwith the physicochemical parameters of the spreading of the oils on theskin, as illustrated by U. Zeidler in Fette, Seifen, Anstrichmitt. 87,403 (1985). According to this reference, cosmetic oils can be classifiedas low-spreading (below 300 mm² /10 mins.), medium-spreading (around 300to 1000 mm² /10 mins.) and high-spreading oils (above 1000 mm² /10mins.).

If a high-spreading oil is used as the oil component in a predeterminedformulation, the required feeling of smoothness of the skin is achievedvery quickly, although the experience does not last long. Conversely, iflow-spreading oils are used, the feeling of smoothness is by no meanspronounced and remains largely unchanged over a relatively long periodso that it is also unsatisfactory. The logical combination of alow-spreading oil with a high-spreading oil surprisingly does not leadto the required additive effect, instead first the strong smoothingeffect of the fast-spreading oil component and then, quiteindependently, the effect of the slow-spreading oil are subjectivelyperceived. In practice, therefore, it is normally necessary to usecomplex mixtures of oils adapted exactly to one another whichsuccessively develop their respective effects on the lines of a cascadewithout adversely affecting one another. It is obvious that thedevelopment of systems such as these involves considerable outlay onequipment and is therefore in need of improvement from the economicpoint of view as well cf. A. Ansmann, SOFW-Journal, 120, 158 (1994)!.

Accordingly, the problem addressed by the present invention was toprovide new cosmetic and/or pharmaceutical formulations which would befree from the disadvantages mentioned above.

DESCRIPTION OF THE INVENTION

The present invention relates to cosmetic and/or pharmaceuticalformulations with an improved feeling on the skin which arecharacterized in that they contain Guerbet alcohols based on fattyalcohol mixtures containing 6 to 12 carbon atoms and/or esters thereofwith fatty acids containing 6 to 22 carbon atoms, the total spreading ofthe oil components according to Zeidler being in the range from about300 to 1000 mm² /10 mins.

It has surprisingly been found that cosmetic or pharmaceuticalformulations which contain Guerbet alcohols based on fatty alcoholmixtures with the chain length mentioned and/or esters thereof as oilsimpart the required instantaneous and relatively long-lasting feeling ofsmoothness to the skin. If, by contrast, Guerbet alcohols based on thepure fatty alcohols are used instead of these Guerbet alcohols or if theGuerbet alcohols based on the pure fatty alcohols are correspondinglymixed, a significantly poorer feeling of the skin is achieved.

In the Guerbetization of alcohol mixtures, mixed Guerbet alcohols arealso inevitably formed. Mixed compounds such as these are neitherpresent in Guerbet alcohols obtained by Guerbetization of the pure fattyalcohols nor are they obtainable by mixing Guerbet alcohols based onpure fatty alcohols. However, the invention includes the observationthat it is precisely the presence of these mixed compounds--obtainedsolely by Guerbetization of fatty alcohol mixtures--which is responsiblefor the surprising skin-care properties of the oils.

The invention also includes the observation that the required effect ofsmoothness of the skin can be further improved if the Guerbet alcoholsmentioned are mixed with other oils, preferably esters of fatty acidswith 2-ethyl hexanol, in such a way that the spreading of the oilmixture corresponds to that of a medium-spreading oil and, according toZeidler, has a value in the range from 350 to 900 mm² /10 mins. It ispointed out even at this juncture that the use of a medium-spreading oilor the use of an oil mixture of which the spreading corresponds to thatof a medium-spreading oil also does not lead readily to the requiredfeeling of smoothness of the skin without the addition of the Guerbetalcohols based on fatty alcohol mixtures.

Guerbet alcohols

Guerbet alcohols are known oils which are normally obtained bybase-catalyzed condensation of fatty alcohols. An overview of thissubject was published by A. J. O'Lennick and R. E. Bilbo in Soap Cosm.Chem. Spec. April, 52 (1987).

Oils suitable for the purposes of the invention are Guerbet alcoholsbased on fatty alcohols containing 6 to 12 and preferably 8 to 10 carbonatoms. Typical examples are Guerbet alcohols based on mixturescontaining caproic alcohol, caprylic alcohol, capric alcohol and/orlauryl alcohol. A typical fatty alcohol mixture within the C chainlength range mentioned is the so-called C_(8/10) head-fractionated fattyalcohol which is obtained as a cut in the distillation of, for example,coconut oil, palm oil or palm kernel oil. A Guerbet alcohol based on afatty alcohol with a C chain distribution of <5% by weight C₆, 50 to 60%by weight C₈, around 35 to 45% by weight C₁₀ and <2% by weight C₁₂ isparticularly preferred.

Guerbet esters

The Guerbet alcohols mentioned above may also be used in the form oftheir esters with fatty acids containing 6 to 22 carbon atoms,preferably 8 to 18 carbon atoms and more preferably 12 to 14 carbonatoms. Typical examples are esters of Guerbet alcohols with caproicacid, caprylic acid, 2-ethylhexyl hexanoic acid, capric acid, lauricacid, isotridecanoic acid, myristic acid, palmitic acid, palmitoleicacid, stearic acid, isostearic acid, oleic acid, elaidic acid,petroselic acid, linoleic acid, linolenic acid, elaeostearic acid,arachic acid, gadoleic acid, behenic acid and erucic acid and thetechnical mixtures thereof obtained, for example, in the pressurehydrolysis of natural fats and oils, in the reduction of aldehydes fromRoelen's oxosynthesis or in the dimerization of unsaturated fatty acids.

The Guerbet esters may have a degree of esterification of 100%, althoughpartial esters with a degree of esterification of 20 to 90% and, moreparticularly, 40 to 70% of the theoretical are preferably used. Estersbased on the above-mentioned Guerbet alcohols with technical C₈₋₁₈ orC₁₂₋₁₄ cocofatty acids which have a degree of esterification of 40 to 70are particularly preferred. Corresponding mixtures of completelyesterified Guerbet esters and the corresponding Guerbet alcohols in aratio by weight of 10:90 to 90:10 and preferably 30:70 to 70:30 areequally suitable.

Oils

The formulations according to the invention may contain other oils ofwhich the choice is not critical as long as the mixture of the oils withthe Guerbet alcohols based on short-chain fatty alcohol mixtures has aZeidler spreading value comparable with that of a medium-spreading oil,i.e. in the range from about 300 to 1000 mm² /10 mins. Examples of oilswhich may be used in the formulations in addition to the Guerbetalcohols mentioned are:

b1) esters of linear C₆₋₂₀ fatty acids with linear C₆₋₂₀ fatty alcohols,

b2) esters of branched C₆₋₁₃ carboxylic acids with linear C₆₋₁₈ fattyalcohols,

b3) esters of linear C₁₀₋₁₈ fatty acids with branched alcohols, moreespecially 2-ethyl hexanol,

b4) esters of linear and/or branched fatty acids with dihydric alcohols,

b5) triglycerides based on C₆₋₁₀ fatty acids,

b6) vegetable oils,

b7) branched primary alcohols,

b8) substituted cyclohexanes and/or

b9) dialkyl ethers.

Typical examples are esters of capric acid and caprylic acid withcocofatty alcohols, esters of coconut oil or palm kernel oil fatty acidwith 2-ethyl hexanol, oleic acid decyl ester, isononanoic acid cetearylester, triglycerides based on capric/caprylic acid, isocetyl alcohol,di-n-octyl cyclohexane, di-i-octyl cyclohexane, di-n-octyl ether anddi-2-ethylhexyl ether.

A combination of the Guerbet alcohols mentioned with fattyacid-2-ethylhexyl esters has also proved to be extremely advantageous.From the sensorial point of view, it is of particular advantage to use amixture of a Guerbet alcohol based on a mixture of fatty alcoholscontaining 6 to 12 carbon atoms and a 2-ethylhexyl ester based on afatty acid with the following C chain distribution: <3% by weight C₁₄,45 to 53% by weight C₁₆, 43 to 52% by weight C₁₈ and <2% by weight C₁₈.

Composition of the formulations

The cosmetic and/or pharmaceutical formulations according to theinvention may contain a) the Guerbet alcohols and/or Guerbet esters andb) other oils which meet the spreading range requirement in a ratio byweight of 100:0 to 10:90, preferably in a ratio by weight of 90:10 to10:90 and more preferably in a ratio by weight of 70:30 to 30:70. Theformulations may be produced by methods known per se, for example byhot, cold, hot-hot/cold or PIT emulsification. These are purelymechanical processes which do not involve a chemical reaction.

Examples of mixtures of the type mentioned are mixtures of a Guerbetalcohol based on a C₆₋₁₂ fatty alcohol mixture with C_(16/18) fattyacid-2-ethylhexyl ester, oleic acid decyl ester, oleic acid oleyl ester,triglycerides based on C_(8/10) fatty acid or isononanoic acid cetearylester in a ratio by weight of 50:50. Further examples are mixtures of aGuerbet alcohol based on a C₆₋₁₂ fatty alcohol mixture with almond oilin a ratio by weight of 90:10 or with di-n-octyl ether in a ratio byweight of 80:20.

In addition, the formulations, for example creams and lotions, maycontain emulsifiers, fats and waxes, stabilizers and superfattingagents, thickeners, biogenic acids, film formers, preservatives, dyesand fragrances.

Suitable emulsifiers are both known w/o and also o/w emulsifiers suchas, for example, hydrogenated and ethoxylated castor oil, polyglycerolfatty acid esters or polyglycerol polyricinoleates or polyglycerolpoly-12-hydroxystearates.

Typical examples of fats are glycerides while suitable waxes are interalia beeswax, paraffin wax or microwaxes, optionally in combination withhydrophilic waxes, for example cetostearyl alcohol.

Suitable stabilizers are metal salts of fatty acids, for examplemagnesium, aluminium and/or zinc stearate.

Suitable superfatting agents are such substances as, for example,polyethoxylated lanolin derivatives, lecithin derivatives, polyol fattyacid esters, monoglycerides and fatty acid alkanolamides, the fatty acidalkanolamides also serving as foam stabilizers.

Suitable thickeners are, for example, polysaccharides, more particularlyxanthan gum, guar guar, agar agar, alginates and tyloses, carboxymethylcellulose and hydroxyethyl cellulose, also relatively high molecularweight polyethylene glycol monoesters and diesters of fatty acids,polyacrylates, polyvinyl alcohol and polyvinyl pyrrolidone; surfactantssuch as, for example, narrow-range fatty alcohol ethoxylates or alkyloligoglucosides and also electrolytes, such as sodium chloride andammonium chloride.

Biogenic acids in the context of the invention are, for example, plantextracts and vitamin complexes.

Typical film formers are, for example, chitosan, microcrystallinechitosan, quaternized chitosan, polyvinyl pyrrolidone, vinylpyrrolidone/vinyl acetate copolymers, polymers of the acrylic acidseries, quaternary cellulose derivatives and similar compounds.

Suitable preservatives are, for example, phenoxyethanol, formaldehydesolution, parabens, pentanediol or sorbic acid.

Suitable pearlescers are, for example, glycol distearic acid esters,such as ethylene glycol distearate, and also fatty acid monoglycolesters and fatty acids.

Suitable dyes are the substances suitable and permitted for cosmeticpurposes as listed, for example, in the publication "KosmetischeFarbemittel" of the Farbstoffkommission der DeutschenForschungsgemeinschaft, published by Verlag Chemie, Weinheim, 1984,pages 81 to 106. These dyes are normally used in concentrations of 0.001to 0.1% by weight, based on the mixture as a whole.

The total content of auxiliaries and additives may be from 1 to 50% byweight and is preferably from 5 to 40% by weight while the non-aqueouscomponent ("active-substance content") makes up from 20 to 80% by weightand preferably from 30 to 70% by weight of the formulations.

Commercial Applications

The cosmetic and/or pharmaceutical formulations according to theinvention may be o/w and/or w/o emulsions, multiple w/o/w emulsions andpurely lipophilic oils or gels. They have fatting properties and imparta rapid, long-lasting and uniformly diminishing feeling of smoothness tothe skin. The problem of the "smoothing gap" is reliably avoided. TheGuerbet alcohols based on short-chain fatty alcohol mixtures and/or thecorresponding esters may be present in the formulations in quantities of1 to 99% by weight and are preferably present in the emulsions inquantities of 5 to 30% by weight, based on the formulations.

The following Examples are intended to illustrate the invention withoutlimiting it in any way.

EXAMPLES

I. Zeidler spreading values

The spreading values of various oils were determined by the Zeidlermethod. To this end, quantities of 4 mg of the oil component wereapplied to the inside of the lower arm of a test subject which had beenrubbed beforehand with cotton wool moistened with ethanol. The test wasconducted in an atmosphere of 23° C./60% relative air humidity. After 10minutes, an impression of the spread lipid was taken with tracing paperand the surface area determined (cf. Table 1).

                  TABLE 1                                                         ______________________________________                                        Spreading (S) of oils  mm.sup.2 /10 mins!                                     Ex.    Oil                     S                                              ______________________________________                                        B1     Almond oil              200                                            B2     C.sub.16/18 fatty acid-2-ethylhexyl ester                                                             800                                            B3     Guerbet alcohol based on caprylic alcohol                                                             700                                                    Eutanol ® G 16!                                                   B4     Guerbet alcohol based on caprylic alcohol                                                             600                                            B5     Oleic acid decyl ester  Cetiol ® V!                                                               700                                            A1     Guerbet alcohol based on C.sub.6/10 fatty alcohol                                                     650                                            A2     Guerbet alcohol based on C.sub.6/10 fatty alcohol/                                                    730                                                   C.sub.12/14 cocofatty acid ester                                       B6     Triglyceride based on C.sub.8/10 fatty acid                                                           550                                                    Myritol ® 318!                                                    B7     Isononanoic acid cetearyl ester  Cetiol ® SN!                                                     700                                            B8     Di-n-octyl ether  Cetiol ® OE!                                                                    1600                                           ______________________________________                                    

II. Subjective evaluation by a test panel

A panel consisting of 5 experienced examiners tested formulations basedon a standard skin cream containing various oil mixtures for theirsubjective feeling of smoothing of the skin. Evaluation was based on ascale of 1 (hardly any smoothing or rapid disappearance of the feelingof smoothness) to 6 (rapid uniform feeling of smoothness).

The figures in Table 2 are average values. Examples 1 to 11 correspondto the invention while Examples C1 to C9 are intended for comparison.

                  TABLE 2                                                         ______________________________________                                        Subjective feeling of smoothness of the skin                                                                   Smoothness of the                            Ex.  Component 1                                                                              Component 2                                                                              Ratio skin                                         ______________________________________                                         1   A1         --         100:0 5.1                                           2   A1         B1         90:10 5.2                                           3   A1         B2         50:50 5.8                                           4   A1         B5         50:50 5.7                                           5   A1         B6         50:50 5.2                                           6   A1         B7         50:50 5.2                                           7   A1         B8         80:20 5.4                                           8   A2         --         100:0 5.1                                           9   A1         A2         50:50 5.8                                          10   A1         A2         70:30 5.6                                          11   A1         A2         30:70 5.4                                          C1   --         B1         0:100 1.5                                          C2   --         B2         0:100 3.5                                          C3   --         B3         0:100 3.0                                          C4   --         B4         0:100 3.0                                          C5   B3         B4         50:50 3.0                                          C6   --         B5         0:100 3.0                                          C7   --         B6         0:100 3.0                                          C8   --         B7         0:100 3.0                                          C9   --         B8         0:100 2.0                                          ______________________________________                                    

Above an average value of 5.0, the feeling of smoothing of the skin isexcellent; below 5.0, the result is unsatisfactory. The results showthat a satisfactory result is only obtained with Guerbet alcohols basedon short-chain fatty alcohol mixtures or esters thereof or with mixturesof these Guerbet alcohols with other oil components within the claimedspreading range.

What is claimed is:
 1. A cosmetic or pharmaceutical composition havingan improved feet on the skin, said composition containing as oilcomponents Guerbet alcohols prepared from mixtures of fatty alcoholshaving differing chain lengths and containing 6 to 12 carbon atoms oresters thereof with fatty acids containing 6 to 22 carbon atoms, whereinthe spreading value of the oil components as determined by the Zeidlermethod is from about 300 to about 1,000 mm² /10 minutes.
 2. Acomposition as in claim 1 containing partial esters of Guerbet alcoholsprepared from fatty alcohol mixtures containing 6 to 12 carbon atomswith fatty acids containing 12 to 14 carbon atoms, and wherein thedegree of esterification of said partial esters is from 20% to 90%.
 3. Acomposition as in claim 1 containing fatty acid esters of 2-ethylhexanol.